“This wanton murder of civilians emphasizes even more a need for investigation under international control of humanitarian crimes in Ukraine. The international community must insist on inevitability of punishment for those behind these evil deeds,” Konstantin Dolgov, ministry’s Commissioner for Human Rights, Democracy and the Rule of Law, posted on his Twitter microblog.

On Tuesday, militia in the self-proclaimed Donetsk People’s Republic (DPR) found a grave at Kommunar mine 60 kilometers from regional centre Donetsk.

“This may be a mass grave. The bodies are to be exhumed, the whole site will be inspected. Other burial sites were found that will be opened,” a militiaman told TASS.

Representatives from the DPR prosecutor’s office said an investigation would be launched.

Militia sources said four bodies have been found so far, some of them beheaded. Two days ago, units of Ukrainian National Guard were stationed there.

The southeastern Ukrainian Donetsk and Lugansk regions have been the scene of fierce clashes between local militias and troops loyal to Kiev seeking to regain control over the breakaway territories, which on May 11 proclaimed their independence at local referendums and now call themselves the Donetsk and Lugansk People’s republics.

On September 5, the trilateral Contact Group on Ukraine (Russia, Ukraine and the OSCE) and representatives of the self-proclaimed Donetsk and Lugansk People’s republics reached an agreement on ceasefire in Ukraine’s embattled southeast, troops withdrawal, exchange of prisoners and provision of humanitarian aid.